I am setting up the midget to be a cruiser and not necessarily revving to 5k. Uncertain how the stock differential can handle the A series power. The individual axle shafts have been known to get distorted and even break over time. I have seen reinforced shafts and may explore that if it becomes a problem. Didn't realize the a12 was that much lighter than the a15. Will save that engine for my next spridget project. The midget tach shows 5500 yellow line and 6000 redline, what is it for the A15?